Retinal Polarimetry Discriminating Algorithms

University of Arizona
posted on 11/03/2009

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Background: Polarization is a significant property of light that can be used to provide imaging contrast in applications where standard imaging produces little.  One such application is found in retinal imaging. In the retina, there are not many strong contrast mechanisms for standard imaging to exploit.  Thus, common eye diseases such as glaucoma, diabetic retinopathy, and Age-related Macular Degeneration (AMD) do not produce easily detectable changes during their early stages, as many ocular structures are transparent while others are obscured by opaque tissues.  To obtain additional information on the retina and other ocular structures, polarization can be used to induce contrast in transparent tissues as well as modify the contrast in tissues with chromophores.  Beyond retinal imaging, polarization has broad utility in characterizing other tissue properties and even general material properties that are not readily visible to standard imaging methods.  The additional information provided by polarization imaging may also be used in applications such as target recognition.  Overall, the development of polarization techniques for improved imaging contrast possesses significant potential in biological and other types of structural imaging.

Summary: A professor at the College of Optical Sciences has developed a method, apparatus, and computer program that performs polarimetric analysis, including in-depth depolarization analysis, which further enhances the contrast mechanisms available to polarization imaging.  This technology takes polarization imaging to the next level by providing the detailed diagnostic information revealed by linear retardance, diattenuation, and depolarization (how the object scrambles polarized light) for all possible polarization states. Reductions in the degree of polarization of light can be due to variations in the object that are below the resolution of the imaging system.  This technology can be used for improving the detection of early stage indicators of retinal diseases as well as for general characterization of inorganic material structures.

Applications:

• Lesion detection in retinal and ocular tissue, including early stage macular degeneration

• Target and texture recognition

• Optical testing

• Crystal analysis

• Surveillance

Advantages:

• Provides far more information than other similar devices

• Complete characterization in a simple and user-friendly program

• The program can be adapted for a broad set of applications

• Easy to implement on present retinal polarimeters, thus reducing cost

Stage of Development:  A prototype has been built and tested, showing successful measurement of the desired polarization parameters. Designs for a retinal polarimeter have also been made.

Status: US Patent issued; Patent No. 7,612,880

Contact:  Amy Phillips

aphillips@optics.arizona.edu

Refer to Case# UA04-005